Uses:Decorative stones, abrasive or scouring stones,
filter media and as a polish, cement and soap additive

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Pumice is a textural
rock and not a rock that is classified by mineralogy or chemistry. It
is basically the solidified foam that forms from a lava rich in volatiles or
gases. When the molten rock is effervescing to the point of forming a
froth and then solidifies, pumice is the result. Pumice has numerous
open spaces or vesicles in the form of round bubbles, linear tubes or irregular
cavities. There is so much porosity in pumice that there is often more
empty space than actual rock and in fact some pumice can float on
water.

Some ocean related volcanoes have produced what are known as
pumice rafts,
which are actual floating mini islands made of rock. These pumice islands
can exist for years floating along the ocean currents. Some may have
been responsible for the distribution of island hopping animals and plants
of the Pacific Ocean. Some pumice islands have been found with plants actually growing
on them.

Pumice differs from obsidian
in that obsidian is all glass and lacks the extensive vesicles of pumice.
Most pumice is acidic/felsic in composition associated with rhyolite
since those lavas tend to have more volatiles, but intermediate and basic
varieties are known to occur. Scoria
is a much heavier ropey volcanic rock with larger but less prolific vesicles
than pumice.

There are many uses for pumice as it is light weight, relatively hard and
can have very sharp edges. It is used in the cosmetics industry as an
exfoliating pad, scouring stones and as an additive in creams and lotions.
Pumice's hardness makes it useful as an abrasive and its light weight
gives it an advantage for use as large decorative rocks for landscaping. Its
porous nature makes it a natural for filters.

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